Earlier this year, anglers caught red and vermilion snapper with wounds straight through their muscle tissue. Now there's talk of grouper and mahimahi in a similar state.

But fishermen and scientists concerned about the health of fish in nearby waters are tired of rumors. They want facts.

Last week, a group of commercial fishermen and marine scientists set out to find the truth.

"We need to know whether there's a problem going on with the fish or not," said Bob Spaeth, a Madeira Beach fisherman and spokesman for the commercial fishing industry. "What we really fear is if there's not a problem with the fish and people perceive that there is problem, then fishermen are going to have a problem marketing their fish, which could collapse the market."

The first two of three vessels launched from the Florida coast last week on one of many 10-day trips around the gulf aimed at catching and studying fish, such as snapper and grouper, two of Florida's most valuable species.

The first left Madeira Beach on Wednesday, and the second from Panama City on Friday. The third boat leaves July 18.

The boats, which will survey water from the Florida Keys to the Texas coast, are staffed by about five people each— two crew members and three researchers.

Their goal is simple, yet ambitious: Determine whether an unusual amount of fish in the gulf are showing signs of disease.

Then the challenge becomes finding out why.

"A lot of people want to say it's BP oil in the water, but that may be very difficult to prove," said William Hogarth, a former federal fisheries official who oversees the Florida Institute of Oceanography, referring to the 2010 Deepwater Horizon oil spill. "We don't know if it's really something to be concerned about yet."

Scientists said they must first figure out whether the abnormalities are widespread. Deformities and bacterial infections are normal, even in unpolluted environments, but masses of sick fish are not, said Steve Murawski, a former fisheries official, now with the University of South Florida, who helped orchestrate the $400,000 gulf study.

If researchers come across what appears to be a "hot spot" of ailing fish, Murawski said, the crew will isolate it and take a closer look using underwater video cameras to find ailing fish without having to lure them in.

"Going back will really tell us if there's a problem, and if there's a problem we'll figure out what to do next," Hogarth said.

This venture marks the first time fishermen are joining forces to tackle the problem.

When the first reports of sick fish began to flood in from anglers last winter, some brought back samples for scientists to study. The abnormal catches were then sent to laboratories for toxicology tests.

No findings have been issued from those screenings, researchers said.

"I don't think any of us anticipated seeing this sort of thing unless it was right early in the oil spill," Hogarth said. "So we felt like it was important to look at it and look at why it might be happening."

Murawski said organizers hope the survey will be completed by the end of August.